TLIF: Bone Grafts and Structural Implants
Part Five of Five
There are various devices that can be used as structural grafts: cages to hold bone grafts or bone graft substitutes such as bone graft extenders, demineralized bone matrix (DBM), and autogenous bone.
The ideal standard of care is to provide an anterior interbody fusion with iliac crest bone graft harvested from the patient at the time of surgery. These grafts can be placed within the cages, as well as anterior to the cages to maximize fusion success. Certainly, as techniques and technology improve; the potential to use biologic substitutes such as bone morphogenetic protein (rhBMP-2) to replace the iliac crest bone harvest is an attractive alternative to today's standard.
Structural implants used in interbody fusions range from bony implants such as fibular allografts, which can be placed with autogenous bone, to titanium or carbon-fiber cages, or resorbable cages. These can be used as an implant containing bone graft or bone graft substitute until fusion occurs.
Proper Fusion Technique
Proper fusion technique is far more important than the distinct implant that is used. Endplate preparation, conforming the endplates to the height and shape of the implant, maximizing the graft endplate contact, and allowing for bone graft or bone graft substitutes to be placed anteriorly to the implants, as well as within the implants will maximize fusion success regardless of the implant used.
The potential for success using this procedure is extremely high if the surgeon follows the principles of proper exposure and fusion technique. This technique especially offers the surgeon an efficient means of dealing not only with posterior neural element disease but discogenic disease, degenerative disc height collapse, kyphotic deformities that can be improved and restored into lordosis, spondylolisthesis or other instabilities that can be reduced or stabilized, and allows the surgeon to provide -- with greatest certainty, a successful posterior spinal fusion with instrumentation.
In doing so, from a unilateral translumbar interbody fusion approach, the surgeon minimizes risk to the neural elements on the contralateral side and avoids the complications and risks and morbidity of an anterior procedure.